Graphitic nanotubes in luminescence assays

Abstract

Graphitic nanotubes, which include tubular fullerenes (commonly called “buckytubes”) and fibrils, which are functionalized by chemical substitution, are used as solid supports in electrogenerated chemiluminescence assays. The graphitic nanotubes are chemically modified with functional group biomolecules prior to use in an assay. Association of electrochemiluminescent ruthenium complexes with the functional group biomolecule-modified nanotubes permits detection of molecules including nucleic acids, antigens, enzymes, and enzyme substrates by multiple formats.

1. A composition comprising a carbon nanotube, an enzyme co-factor attached to the outer surface of said carbon nanotube, and an electrochemiluminescent label attached to the outer surface of said carbon nanotube, wherein said enzyme co-factor is selected from the group consisting of NADH, NADPH, NAD+, NADP+ and a derivative thereof. 
     
     
       2. The composition of  claim 1 , wherein said electrochemiluminescent label comprises a metal atom. 
     
     
       3. The composition of  claim 2 , wherein said metal is Ru, Os or Re. 
     
     
       4. The composition of  claim 2 , wherein said metal is Ru. 
     
     
       5. The composition of  claim 1 , wherein said electrochemiluminescent label is Ru(bpy) 3   2+ . 
     
     
       6. The composition of  claim 1 , wherein said electrochemiluminescent label is attached to said the outer surface of said carbon nanotube via a functional group. 
     
     
       7. The composition of  claim 1 , wherein said enzyme cofactor attached to said the outer surface of said carbon nanotube via a functional group. 
     
     
       8. The composition of  claim 6 , wherein said functional group is COOH. 
     
     
       9. An assay composition comprising (i) the composition of  claim 1  and (ii) an enzyme and/or enzyme substrate. 
     
     
       10. A kit comprising, in one or more containers, (i) the composition of  claim 1  and (ii) an enzyme and/or a enzyme substrate. 
     
     
       11. The composition of  claim 9 , wherein said enzyme is dehydrogenase. 
     
     
       12. The assay composition of  claim 11 , wherein said dehydrogenase is glucose dehydrogenase. 
     
     
       13. The kit of  claim 10 , wherein said assay composition comprises said enzyme and said enzyme is dehydrogenase. 
     
     
       14. The assay composition of  claim 11 , wherein said enzyme substrate is a substrate of dehydrogenase. 
     
     
       15. An assay composition comprising (i) the composition of  claim 1 , (ii) an enzyme and (ii) a substrate to said enzyme. 
     
     
       16. The assay composition of  claim 15 , wherein said enzyme is dehydrogenase and said substrate is a substrate of dehydrogenase. 
     
     
       17. A method for detecting the presence or amount of analyte in a sample comprising:
 (a) contacting said sample with an assay composition containing the composition of  claim 1 , wherein the presence of an analyte of interest causes oxidation or reduction of said enzyme co-factor; and 
 (b) detecting or measuring electrochemiluminesence emitted from said electrochemiluminescent label; 
 (c) correlating said electrochemiluminesence to the presence or amount of analyte in a sample. 
 
     
     
       18. The method of  claim 17 , wherein said analyte is an enzyme and said assay composition further comprises a substrate of said enzyme or said analyte is an enzyme substrate and said composition further comprises an enzyme for said enzyme substrate.